Google will not reveal how many search histories it has been asked to change, following the European court of justice ruling in the 'right to be forgotten' case. Photograph: Regis Duvignau/Reuters

Google has begun removing search links to content in Europe under the "right to be forgotten" ruling, which obliges it not to point to web pages with "outdated or irrelevant" information about individuals.

Searches made on Google's services in Europe using peoples' names includes a section at the bottom with the phrase "Some results may have been removed under data protection law in Europe", and a link to a page explaining the ruling by the European court of justice (ECJ) in May 2014.

However searches made on Google.com, the US-based service, do not include the same warning, because the ECJ ruling only applies within Europe.

Google would not say how many peoples' search histories have been tweaked, nor how many web pages have been affected. The company revealed in an interview with chief executive Larry Page at the end of May that it had received thousands of requests for changes to search results within days of the ECJ ruling.

Google has set up an online form where people can request removal of links, and says people can appeal to data protection authorities if they disagree with its decision.

The ECJ ruling followed a court case brought in Spain by Mario Costeja González, a lawyer who argued that under the European Data Protection directive any company carrying out "data processing" should have to remove information about him that was "outdated, wrong or irrelevant" which he argued applied to a Spanish newspaper's online report in March 1998 about financial problems he had had.

The ECJ ruled that the newspaper's report was protected under freedom of expression, but that Google's links to it were not, because Google was a "data processor".